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- It belongs to Heat stress transcription factors (Hsfs),Heat stress transcription factors (Hsfs) are the central regulators of defense response to heat stress.Hsfs diversify in their biological functions . HsfA members are capable of transcriptional activation,while HsfB members act as repressors or as co-activators (e.g., HsfB1) of HsfA members . However,AtHsfA4 activity was reported to be repressed by AtHsf5, which belongs to class A Hsfs. Overexpression of Hsf genes in transgenic plants resulted in an up-regulation of heatstress-associated genes and an enhancement of thermotolerance, whereas the down-regulation of Hsf genes leads to a reduction in the thermotolerance.
- AtHsfA9 is involved in seed development and controlled by seed-specific transcription factor abscisic acid-insensitive 3 (ABI3).Further studies to elucidate the functions of the other members in the subfamily may also have potential for the development of transgenic plants with improved stress tolerance.
- Temperatures above the normal optimum are sensed as heat stress (HS) by all living organisms. HS disturbs cellular homeostasis and can lead to severe retardation in growth and development, and even death. As sessile organisms, plants are constantly exposed to changes in temperature and other abiotic factors.The accumulation of heat shock proteins (HSPs) under the control of heat stress transcription factors (HSFs) is assumed to play a central role in the heat stress response (HSR) and in acquired thermotolerance in plants and other organisms. Our current understanding of the functions of HSPs and HSFs has been summarized comprehensively in several recent reviews.This indicates that an ABA pathway may be involved in Hsf induction and responsible for control of downstream processes, such as seed development or drought resistance。In this study, eight OsHsfs (OsHsfA1a, OsHsfA2b, OsHsfC1b, OsHsfA3, OsHsfA7, OsHsfA9, OsHsfB2c, and OsHsfC1b) were found to be induced by both heat shock and H2O2 . Heat stress led to the accumulation of H2O2 in tobacco and Arabidopsis culture cells and mustard seedlings.
- Expression patterns of OsHsfs:The number of ESTs for a specific gene in a cDNA library is considered to be proportional to the transcript abundance of the mRNA.OsHsfs were expressed at a higher level in panicle and flower than in other tissues.
- The transcription of OsHsfA9 was up-regulated by both HS and H2O2 treatments in a similar manner.
- In Arabidopsis, the heat stress-induced H2O2 is required for effective expression of heat shock genes.
- HSPs were first identified as proteins that are strongly induced by HS. They include Hsp100/ClpB (eukaryotic/ Escherichia coli nomenclature), Hsp90/HtpG, Hsp70/DnaK, Hsp60/GroEL and small HSP (sHSP) proteins.These HSPs are proposed to act as molecular chaperones in protein quality control. The families of HSP genes in plants are complex; because many family members are also essential for normal growth and development, it has been difficult to unravel their roles during stress (and references therein). Other than by extrapolation from their molecular chaperone activity, there is still no specific information on how Hsp70, Hsp90 and Hsp60 contribute to survival of heat stress in plants. With regard to function during heat stress, investigations of Hsp100/ClpB and sHSPs are the most advanced.Genetic analyses in Arabidopsis indicate that Hsp101 interacts with the sHSP chaperone systemto resolubilize protein aggregates after heat stress, a process that requires complex interactions of Hsp101 protein domains.
- Phylogenetic analysis of OsHsfs indicates that the classes A, B and C Hsfs formed three individual clusters. Furthermore, the class A Hsfs were divided into two sub-clusters In a previous study, the N-terminal part and C-terminal part of DBD and HR-A/B regions were used separately to draw phylogenetic trees.Although most proteins fixed their positions in the different phylogenetic trees, a few Hsfs changed their positions.Similar phenomenonwas also observed on the OsHsfs . A more convinced relationship of the Hsfs was revealed by combining the DBD, HR-A/B, and the flexible linker between DBD and HR-A/B.
Labs working on this gene
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Science, Zhejiang University, China
- Department of Molecular Cell Biology, JW Goethe University,Biocenter, Max-von-Laue-Strasse,Germany
- Department of Biochemistry and Molecular Biophysics,University of Arizona, USA
- Chuang WANG, Qian ZHANG, Hui-xia SHOU et al. (2009) Identification and expression analysis of OsHsfs in rice.Journal of Zhejiang University SCIENCE B 10(4):291-300.
- Baniwal, S.K., Bharti, K., Chan, K.Y., Fauth, M., Ganguli, A.,Kotak, S., Mishra, S.K., Nover, L., Port, M., Scharf, K.D.,Tripp, J., Weber, C., Zielinski, D., von Koskull-Döring,P., 2004. Heat stress response in plants: a complex game with chaperones and more than twenty heat stress transcription factors. J. Biosci., 29(4):471-487.
- Charng, Y.Y., Liu, H.C., Liu, N.Y., Chi, W.T., Wang, C.N.,Chang, S.H., Wang, T.T., 2007. A heat-inducible transcription factor, HsfA2, is required for extension of acquired thermotolerance in Arabidopsis. Plant Physiol.,143(1):251-262.
- Kotak, S., Larkindale, J., Lee, U., von Koskull-Döring, P.,Vierling, E., Scharf, K.D., 2007a. Complexity of the heat stress response in plants. Curr. Opin. Plant Biol., 10(3):310-316.